You're going to want to set the div's onmouseover attribute equal to a function. For example, if your div has an id of "thediv", you can attach a function to its onmouseover event like this:

document.getElementById("thediv").onmouseover = function() {
// code to run when the user hovers over the div
};

Or if you've already defined a function named "theFunc", you can do it like this:

function theFunc() {
// code to run when the user hovers over the div
}
// Make sure not to put parentheses after the function name on the following line
document.getElementById("thediv").onmouseover = theFunc;